


your secret (my heartbeat)

by akaparalian



Category: Shadowhunters (TV)
Genre: Clothed Sex, M/M, Possessive Sex, Semi-Public Sex, Sharing Clothes
Language: English
Status: Completed
Published: 2019-02-07
Updated: 2019-02-07
Packaged: 2019-10-24 07:28:41
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,608
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17700176
Author URL: https://archiveofourown.org/users/akaparalian/pseuds/akaparalian
Summary: Magnus — Magnus who wouldn’t ususally be caught dead outside of his loft looking anything but his absolute best; Magnus who glitters and gleams and shines; Magnus who has a seemingly bottomless closet of embroidered waistcoats, sheer, gauzy tops, and perfectly-tailored pants — is wearing a too-big, worn-out shirt with a slightly frayed neckline. It’s threatening to slip off one shoulder, revealing the gorgeous cut of his collarbone; the necklaces dripping from around his throat contrast with the slightly faded black fabric in a way that accentuates both.It’s Alec’s shirt.His.He swallows hard.





	your secret (my heartbeat)

**Author's Note:**

  * For [Dark_Labyrinth](https://archiveofourown.org/users/Dark_Labyrinth/gifts).



> Happy Valentine's day, Dark_Labyrinth! I hope you enjoy this. I loved what you said in your requests about development in Magnus and Alec's relationship, making it stronger than ever, and I wanted to try and play with both intimacy and very public displays, and the ways they intersect, to try and bring that through. I had a great time writing this!
> 
> Title very loosely adapted from the lyrics of "Safe With Me" by Sam Smith.

The briefing isn’t quite interesting enough to command the constant attention of its audience, but the mission is complicated enough to demand it. Alec is good at this, though. This, out of all the duties he’s taken on as Head of the Institute, he not only enjoys and has experience with, but is naturally well-suited to. He doesn’t think of himself as inherently charismatic — Izzy got most of _those_ genes — but he’s good at the attention to detail and the analytical thinking that let him prepare and deliver good mission briefings. Maybe they’re a _little_ on the dry side, but he doesn’t usually get a lot of complaints. 

It’s a missing persons case — missing fairies case, to be precise — and there’s a whole cloud of Seelie Court politics that makes it about ten times more complicated than it needs to be, and the mission team needs to understand that before he lets them leave the Institute, or _he’ll_ be the one who ends up explaining to the Seelie Queen why his Shadowhunters made a mess of things, and Alec generally tries to interact with Her Majesty as little as possible. So, suffice to say, he’s breaking out what Jace calls the “murder eyes,” doing his level best to impress upon the team the importance of what he’s saying, when movement on the other side of the ops room catches his attention.

His first instinct is to smile, because he’d recognize that silhouette anywhere and instantly; his second is to choke on his own tongue, because it takes a second to get beyond the general sense of _Magnus is here!_ and actually process what he’s seeing, but once he does, he stops cold in the middle of a sentence.

Magnus — Magnus who wouldn’t ususally be caught dead outside of his loft looking anything but his absolute best; Magnus who glitters and gleams and shines; Magnus who has a seemingly bottomless closet of embroidered waistcoats, sheer, gauzy tops, and perfectly-tailored pants — is wearing a too-big, worn-out shirt with a slightly frayed neckline. It’s threatening to slip off one shoulder, revealing the gorgeous cut of his collarbone; the necklaces dripping from around his throat contrast with the slightly faded black fabric in a way that accentuates both.

It’s Alec’s shirt. _His_.

He swallows hard.

Someone clears their throat politely, and Alec tears his gaze away from Magnus to refocus on the team of Shadowhunters he’s supposed to be briefing. “Um,” he says indelicately, coughing a little, trying to cover up his momentary distraction and pretend that it was anything other than what it was. The team seems to have followed his sight line, though, and there are now a few smirks and knowing raised eyebrows aimed in his direction, which at least serves the purpose of making the murder eyes much easier to summon.

“Um,” Alec says again, trying to remember what he’d been saying beforehand and, above all else, trying to avoid looking over at Magnus, or _looking_ like he’s looking over at Magnus, even though he can see Magnus making his way across the room in his peripheral vision and can practically feel it like a sense of impending doom as he gets closer and closer. 

It’s stupid, really, Alec thinks wildly, because that shirt ought to look _terrible_ on Magnus. It ought to look terrible on _anyone,_ because it _is_ terrible; Izzy can roll her eyes at his wardrobe all she wants, but he’s not blind and he’s not stupid and he knows enough to know that that shirt is old and ugly and should probably have been thrown out a long time ago, and it definitely _is not_ sexy, and Magnus may be quite literally magical, but even he shouldn’t be able to make a shirt that is _that_ gross look _that_ sexy.

And yet, here they are.

“I’m sorry, what was I saying?” he asks the team he’s briefing, desperately trying to get back on track.

The team laughs at him, and they don’t even doing a good job of hiding it; Alec glares at them until they quit it, but they don’t even really look cowed, just amused and acquiescent. Maybe he’s losing his touch — or maybe it’s just that he keeps interrupting his own glaring to sneak glances at Magnus, who’s not even coming anywhere near him. He’s talking to Raj instead, which makes sense, because Raj has been handling a lot of maintenance and operations-type tasks lately, which likely includes whatever Magnus is here if it’s not dangerous or pressing enough for Alec to have been alerted. It’s probably something to do with the wards, or analyzing some piece of evidence for a case, or something else relatively minor. It’s fine. This is _fine_. Alec is going to continue giving this mission briefing, just as soon as he remembers what the hell he was talking about, and everything is going to be _fine_.

He looks down at the mission dossier in his hands, both out of a desperate lack of anything else to do and the general hope that maybe that will remind him where he was in the briefing. It almost works — or, rather, it mostly works, and he’s confident enough in his recovered train of thought to try glaring again and say, “Okay, seriously, listen up. The joke is over,” even though _he’s_ the joke, and the team mostly settles down again and falls in line for long enough for him to get through the rest of the briefing.

“Any questions?” Alec asks a few minutes later, and when it seems that the answer is no, he nods and dismisses them and waits what he thinks is probably a socially acceptable amount of time before he spins around, searching for Magnus in every corner of the ops room.

He’s not there, because of course he isn’t, but the image of him in that shirt is more or less burned into Alec’s retinas at this point, and Alec only really stops to think about it for a few seconds before he swallows his pride and stalks across the room to talk to Raj.

“He’s consulting on a case,” Raj says before Alec can even open his mouth, as soon as he’s in earshot. “I don’t know when he’ll be done, but he went with Amelie, Troy, and Suyin to go have a look at that warehouse in Greenpoint with the weird energy readings.”

Alec knows exactly what he’s talking about, and for a moment, anyway, he’s blessedly distracted from thoughts of Magnus’ collarbones by thoughts of the thing he’s currently off investigating, which they hadn’t been able to make heads or tails of but which had been decidedly demonic in nature — and if there’s one thing in this world Alec’s learned to be extra wary of, it’s the demons they _don’t_ know about, rather than the ones they do. 

“Okay,” he tells Raj, “thanks,” and then he has to — somewhat grudgingly — go back to his office and get work done, because there’s no way he can interrupt Magnus if he’s working on a case like that. Not for any of the reasons he _wants_ to interrupt him, anyway. 

The next few hours are torture. Running an Institute comes with a lot of paperwork, and normally, Alec’s fine with that. He actually kind of enjoys it — the bureaucracy of it is comforting, once he gets in the groove, and he’s always had a knack for remembering details. When he was a kid, that usually translated to really good grades on his history assignments, and now it’s put to what’s probably much better use. 

On an average day, the short stack of forms and reports waiting for him on his desk wouldn’t take him longer than an hour, at most. Today, it takes him three, because he can’t go longer than thirty seconds at a stretch without thinking about Magnus, who might be back in the Institute, _right now_ , wearing his shirt. Can everyone who sees him tell that it’s Alec’s? Alec can’t decide if he hopes they can, because he likes the idea that they know that he’s Magnus’ and Magnus is his, or if he hopes they can’t, because Magnus all wrapped up in him is something that feels incredibly personal, private, just for him — even if Magnus wearing the shirt in public means that, by definition, it isn’t just for him.

And why _now_? Is there some particular reason? Magnus hasn’t ever done anything like this before. Obviously, their relationship is far from a secret in the halls of this Institute — something that’s technically more Alec’s doing than Magnus’ — and neither of them makes any real attempt to be subtle about it, but this feels like another level, because something about it feels so _intentional_. It’s designed to provoke, and he’s not sure if there’s a reason why, or if it was just a whim, or if maybe he’s overthinking the whole thing and Magnus hadn’t meant half as much by it as Alec’s assuming he had.

He spends all afternoon with his thoughts tangled up and crosswired, and by the time he’s finally getting close to finishing up his stack of paperwork, he glances down at the clock and groans when he realizes how late it’s gotten. Then he brightens because, if it’s been that long, surely — 

The knock on his office door sends his heart racing. “Come in,” he calls, working hard to keep his voice steady.

It’s Magnus, thank God — Alec doesn’t know what he would have done if it wasn’t. He locks the door behind him, which makes Alec’s heart beat impossibly faster; he’s starting to feel almost lightheaded with anticipation and desire, because Magnus doesn’t look as good as Alec remembers. He looks _better_.

“Are you trying to kill me?” Alec asks him frankly, still sitting at his desk. Magnus grins and saunters over, easily hopping up onto the corner of the desk and leaning down for a kiss — just a quick peck, nothing like the way Alec _really_ wants to kiss him, but, he hopes, they’ll have time for that. For now, they haven’t seen each other all day.

“Maybe a little,” Magnus says, shimmying his shoulders a little in a way that shows off exactly how well the shirt drapes over his chest. “Why, is it working?”

“Yes,” Alec groans, leaning back in his chair a little to get a better look at Magnus sitting there on his desk, one leg crossed over the other, leaning forward _just so_ so that Alec can see his chest through the gaping collar of the shirt. Honesty seems the best policy; he’s not interested in playing coy at the moment. He’s a little too desperate for that, and Magnus seems to be on the same page, leaning forward even further so that he stays in Alec’s space.

“Do you want me to tell you what I found at that warehouse now, or later?” Magnus teases, his eyes glittering in the light from Alec’s desk lamp.

It’s almost painful to do, but Alec forces himself to stop and really consider that, deliberating. It was clearly a joke, but still. “Is Brooklyn going to explode if I say no?”

Magnus laughs. “Almost certainly not.”

“Then kiss me,” Alec says, and Magnus is already moving to close the gap between them before the words are even all the way out of his mouth.

He slides right off the desk and into Alec’s lap, knees slotting on either side of Alec’s hips. Alec groans and immediately grabs for leverage, his fingers tightening in the fabric of the shirt — _his_ shirt — in a way that somehow turns him on even more. Magnus loops his arms easily around Alec’s neck, and the kiss they exchange is full of teeth and tongue and the promise of everything that’s been racing through Alec’s mind for hours now.

It’s a struggle, but he pulls back, gasping, just enough to ask, “Did you lock the door?”

Magnus kisses him again, long and slow, and murmurs, “No.”

“ _Can_ you lock the door?” Alec manages, in between taking deep, heaving lungfuls of air, trying to keep his focus on these last few practicalities before he gives himself over completely.

“Hmmm,” Magnus says, and that alone — the little hum, and the wicked little quirk of his lips — is enough to make Alec’s heart beat somehow faster, never mind the way he slowly, deliberately grinds his hips down and makes it perfectly clear that they’re both hard. “What if I didn’t? I’m sure the whole Institute knows not to come in.” 

“Fuck,” Alec breathes, his fingers clenching and unclenching thoughtlessly in worn cotton.

Magnus smiles, scratches his nails deliciously through the hair at the nape of Alec’s neck, and leans in a little closer, leaning their foreheads together until his lips nearly brush Alec’s skin as he speaks. “They all saw the way you looked at me in the ops room,” he adds. “I don’t think anyone’s got any doubt about what’s happening right now.”

“ _Fuck_ ,” Alec repeats, with feeling, and then, “God, _Magnus_ —” 

He takes a split second to deliberate — more, if he’s being honest, than he might have expected from himself in this situation — and then he surges up, lifting with hands on Magnus’ waist and setting him down on the desk, shoving himself between Magnus’ legs and then pushing against his chest until Magnus is laid out flat across the top of the desk, the piles of paperwork that had occupied Alec’s entire afternoon going flying to the floor on either side of them. Alec kisses his lips, his jaw, his neck, even as he works at the button of the damnably tight leather pants that Alec had hardly even _noticed_ amidst the distraction of the shirt, which now seems like a crime.

He gets Magnus’ pants open and shimmies them down his hips with a little help, and then off all the way and tossed dismissively to the floor, and then makes quick work of his underwear as well, but when Magnus starts to reach for the hem of the shirt to pull it off over his head, Alec shakes his head and says, “No.”

Magnus stops, raising an eyebrow, his smile knowing. “No?”

“No,” Alec repeats, leaning in again to kiss him. “Leave it on.”

“Your wish,” Magnus murmurs, returning the kiss eagerly; he sounds amused, knowing, but Alec’s not exactly bothered by that, and besides, the thought’s out of his head the instant their lips touch again. Magnus arches his body up against Alec’s, the two of them pressed close everywhere, and Alec hisses into the kiss as their hips grind together again, just a tease, really.

“Okay,” he says inanely, mostly to himself, pulling back and using one hand to pin Magnus down to the desk so he doesn’t do it again. Alec is on a mission now, damn it, and as much as part of him would like to just keep kissing and rubbing against each other, Magnus spread out half-naked on the desk underneath him, until he comes in his pants and Magnus makes a mess all over the shirt… Well, the thought distracts him for a moment, but there are still other things he wants more.

“Okay,” he repeats, and waves the fingers of his free hand in a vague imitation of Magnus’ casting. “Could you…?”

Magnus snaps his fingers, and there’s a bottle of lube in Alec’s hand — the one from their bedside table, in fact, which at least means that Magnus hasn’t stolen it from someone in the Institute, which might have made for a very, very awkward conversation. Alec pops the cap and begins liberally slicking his fingers, and Magnus props himself up on his elbows, drawing his legs up and out of the way.

Alec gets himself nice and comfortable, leaning over and pushing Magnus back a little, pulling one leg up over his shoulders. He runs his fingers down the curve of Magnus’ ass and then rubs a light circle over his rim, testing the waters. Magnus makes a throaty noise of encouragement, staring down between them — Alec tries not to block the view — and then, when Alec slowly, deliberately presses his first finger in, he throws his head back and sighs.

It’s not until the second finger — not that that takes very long, considering they did this only a few nights ago, but Alec likes to be thorough — that Alec can’t handle Magnus’ cock only inches from his face anymore, and leans forward to suck it gently into this mouth, focusing on the head and trying to keep it loose, more of a tease than anything. Magnus has been teasing him, after all; he doesn’t see why he shouldn’t be allowed to give as good as he gets.

Magnus takes in a sharp breath when Alec’s lips close around his cock, and then when Alec sucks lightly, he sighs it back out again, tugging gently at Alec’s hair and shooting a soft, amused smile down at him.

“What, were you getting bored down there?” he asks, and Alec rolls his eyes at him, which probably looks extra ridiculous with his mouth full of dick. He does speed up his fingers, though, because he certainly doesn’t want _Magnus_ getting bored, and also because — well. Bored isn’t the right word at all, but he definitely is starting to get impatient.

“You ready?” he asks only a couple of minutes later, pulling off of Magnus’ cock but leaving his fingers inside; it’s a genuine question, becuase he hasn’t really done all the stretching that’s probably necessary, but Magnus likes it that way sometimes, and they’re both obviously on edge. 

Magnus hums consideringly and clenches down on Alec’s fingers, deliberating, and then says, “Yes,” and as soon as the word is out of his mouth, they’re both in motion, Alec getting back up in his desk chair and Magnus sitting up fluidly and sliding right back into his lap. Alec only barely has time to get his pants unbuttoned and shoved far enough down to get his dick out before Magnus is hovering over him, holding himself up with hands on Alec’s shoulders.

“Ready?” Alec asks again, checking base even though he’s not the one in control here — Magnus can move whenever he damn well wants to — and this time Magnus’ response is much more immediate.

“Ready,” he says, nodding, and Alec steadies him with a hand on his waist and uses the other to hold himself still as Magnus sinks slowly, inexorably down onto him.

They both cry out at the feeling, soft groans mingling between them as Alec grits his teeth to keep still and Magnus pants as he slowly, slowly brings his hips down. He moans much more loudly when he’s finally settled all the way down in Alec’s lap again, shifting his hips experimentally and making an appreciative noise at what he finds. Then, while Alec’s still adjusting — Magnus is so hot around him, and so _tight_ , and Alec had known he would be, had known that he hadn’t really quite stretched him enough, but it feels like another level, somehow, and he’s gone boneless in the chair, only barely managing to stay sitting up enough to keep the both of them from sliding to the floor — Magnus starts to move, and it’s Alec’s turn to let out a much louder, much more shocked grunt.

“Jesus,” he hisses, and Magnus laughs breathlessly as he slowly levers himself up and then inches back down, undulating his hips in a smooth, easy motion and tipping Alec’s chin up to kiss him briefly.

“Hmm,” Magnus says when he pulls back, grinning. He blinks, and suddenly his cat’s eyes are out; maybe it’s just a conditioned response, considering Alec sees them most often when they’re having sex, but the sight of them makes him shiver in his seat with an extra pang of desire. “I knew that shirt was a good idea.”

“ _Great_ idea,” Alec manages breathlessly, then groans as Magnus carefully, deliberately pulls himself up and then down again.

“You know I’ve always valued my independence,” Magnus says, almost conversationally, as he rides Alec so slowly that Alec thinks, for a moment, that he might die just like this. He makes a wordless noise in response, not quite sure where Magnus is going with this but also not quite able to fully focus on what he’s saying at the moment in favor of ensuring that he keeps breathing and doesn’t let his grip on Magnus’ waist get too bruising.

“But I also value being yours,” Magnus continues, and at that, Alec forces himself to pay a little more attention. He looks up into Magnus’ face, their normal height difference more or less reversed by their position, and catalogues the things he can see there: fondness, and love, and want, and a little bit of humor, and something almost sad, something he can’t quite put a name to, but that makes him reach out and brush a stray strand of hair off of Magnus’ forehead, his fingers trembling.

“Magnus…” he breathes, and Magnus smiles at him and then starts to move his hips a little faster.

“And,” Magnus says, as though Alec hadn’t interrupted, “I want _everyone_ to know how much I love you, Alexander. Every single person that sees me.”

Alec swallows hard. “ _Magnus_ ,” he repeats, with feeling, and then, “I love you too, Magnus, oh my god—”

“I want _everyone_ to know that we belong together. I want them to know, when I’m at the Institute, to knock every time before they walk into your office,” Magnus says, moving faster and faster, and it’s so much. It’s _too_ much, and Alec’s been on edge for hours, wanting this, needing this — needing Magnus, and needing the closeness, the way they’re pressed so tightly together that it’s impossible to draw them apart. 

“Fuck,” he chokes out, and draws Magnus down for a kiss, needing it more than he can even describe. Magnus kisses back eagerly, and by the time they pull apart, Alec is breathing harder than ever and so incredibly close to the edge that he viciously pinches his thigh to draw things out a little longer, trying to hold himself back. “Magnus,” he says, “Magnus, I’m not gonna…”

Magnus smiles.

“And,” he says, his voice dropping low and velvet-soft, “I like that you’re mine. I like that I can make you desperate. Are you desperate, Alexander?”

Alec swears at him, grinning. “What do you think?”

“Well,” Magnus replies, laughing breathlessly, “don’t let me stop you, then.”

But he’s close, too; Alec knows it too well to miss the signs. He’s bluffing, Alec thinks, at least a little bit, trying to maintain the impression that he’s completely in control and making Alec fall apart. Alec’s fine with that, and it is, after all, _mostly_ true, but it’s not the complete truth, and Alec wants to see him fall apart, too.

He reaches between them with a little bit of difficulty and fits his hand around Magnus’ cock, which is, sure enough, hard enough now that it feels like it must almost hurt, slick with pre-come and twitching in Alec’s hand as he squeezes gently, testing the water. Magnus gasps, and Alec leans forward a little to bite teasingly at his collarbone as he starts to stroke in earnest.

It doesn’t take very long at all until Magnus is reduced from riding him to just grinding down onto his cock, which is really the only reason Alec makes it as long as he does. He crests over, though, before Magnus, does, and grabs at his waist in an attempt to get even deeper inside him as he groans loudly and buries his face in the crook of Magnus’ neck and comes so hard he forgets to breathe.

There’s a long moment of rippling aftershocks before he gets his faculties back well enough to get a proper grip on Magnus’ dick again, but that’s fine; Magnus is shifting his hips in tiny increments in the meantime, just on the edge of too much for how sensitive Alec is after he comes, and it’s only a few more slick, loose-wristed strokes before he’s coming — and, just as Alec had hoped he might, he comes all over the shirt. Alec watches, rapt, at the splatter against the dark fabric, and wonders at the idea that the stupid thing belongs to both of them now. 

“Fuck,” he exhales in the moments after, and there’s a beat of silence before Magnus huffs a laugh, reaching out to gently stroke a thumb across Alec’s cheekbone.

“My sentiments exactly,” he quips, and Alec shakes his head mutely, laughing breathlessly.

There’s a pause, neither of them, clearly, willing to being the process of moving and untangling and cleaning up and re-dressing, even though doing all of that means going home, laying together on the couch, probably, and enjoying more closeness. Then Alec takes a deep breath, holds it, thinking, and lets it out, squeezing where he’s still holding Magnus’ waist with one hand.

“I love you too, you know,” he says quietly, and Magnus makes a soft, murmuring noise of assent. There’s probably very little doubt there, Alec thinks wryly, and after all, he hadn’t really meant it as reassurance, so much as he just felt that it needed to be said. “I honestly still can’t believe you did this. This shirt’s not exactly your usual style.” He tugs at it for emphasis, carefully picking a dry spot, and then, unable to help himself, he rucks it up over Magnus’ abs, watching the way the fabric moves against his skin with rapt attention.

“Don’t expect me to do it every day,” Magnus says, dry, and meets Alec’s answering laugh with a smile before continuing, “but I think I’ve explained thoroughly enough that the idea appeals to me.”

“It appeals to me, too,” Alec says, and this time Magnus laughs, then gasps in affected shock.

“ _Really?!”_ he exclaims, and Alec bows his head, muffling a snort of laughter against Magnus’ chest. “I couldn’t tell at all! You’ve _got_ to be more clear about these things, love.”

Alec snorts, then leans back and reaches up for a kiss: soft and tender and slow, this time. He pulls away after a moment, but hovers nearby for long enough that Magnus makes a soft questioning noise. Alec sighs, then slowly pulls back, looking with no small amount of regret at the paperwork that’s now spread liberally all over his floor.

“You should probably tell me about that warehouse,” he says, with no small amount of reluctance, and Magnus makes a noise that’s just affirmative enough to register as acknowledgement without crossing the line into assent.

“Mmm,” he says, clenching just slightly around where Alec is softening inside him in a way that makes Alec gasp and then chuckling a little at the glare he gets in response. “In a minute.”

Alec nods, and Magnus leans forward to gently press their foreheads together — sticky, and a little gross, but familiar and comforting all the same. There will be time, Alec thinks, to worry about the warehouse in Greenpoint and the demons that may or may not be infesting it, and to worry about the gossip about them that’s no doubt flying through the Institute at this very moment, and about a hundred other things besides. For now, he lets his eyes drift shut and focuses on Magnus, and on the moment, the both of them here, together, twined together tightly enough that he can let himself believe they won’t ever come apart.


End file.
